Question : Why would a systems be setup with static DNS server addresses?

I've recently been hired to "babysit" a very small office network/work group.

The path to the systems is from the Internet connection is: DSL modem, (which actually functions as a bridge) a old/no long supported Cisco PIX 501 firewall router, then the system(s).  

About 6 weeks ago a user's system could ping nodes on its intranet but couldn't see the Internet.  To my surprise I found the TCP/IP settings were set to have a static IP address and DNS server.  I check the three other systems and they were all set to have static DNS server addresses as well.  But, all different addresses!  I changed the DNS address to match one of a working system and viola it started working.  (I just found out that the address it was set to 4.2.2.2 which is Google.)

Yesterday the same thing happened on another system: Could ping intranet but not Internet.  I changed DNS server address to 4.2.2.2 and it could then ping/connect to the Internet.

My question: shouldn't I be able to set the IP address and DNS server address to "obtain IP address automatically" and let the Cisco Pix 501 handle assigning the addresses for clients hanging off it?

Thanks so much!!!!

Answer : Why would a systems be setup with static DNS server addresses?

If the Cisco PIX is configured as a DHCP server, then yes, you should be able to configure your client workstations to obtain an IP address dynamically from the server itself.

Here's an example from the Cisco site on how to configure a DHCP server on the Cisco PIX - http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a00806c1cd5.shtml.

Hope this helps...

Mike